plates_for_weight

also add different weight_lb for bars

inventory/migrations/0001_initial.py

@@ -16,6 +16,7 @@ class Migration(migrations.Migration):
                 ('id', models.AutoField(verbose_name='ID', auto_created=True, serialize=False, primary_key=True)),
                 ('name', models.CharField(max_length=100)),
                 ('weight_kg', models.DecimalField(max_digits=7, decimal_places=3)),
+                ('weight_lb', models.DecimalField(max_digits=7, decimal_places=3)),
             ],
         ),
         migrations.CreateModel(

inventory/migrations/3000_initial_data.py

@@ -7,8 +7,8 @@ from django.db import models, migrations
 def make_bars(apps, schema_editor):
     Bar = apps.get_model('inventory', 'Bar')
     Bar.objects.bulk_create([
-        Bar(id=1, name="Men's Olympic", weight_kg='20'),
-        Bar(id=2, name="Women's Olympic", weight_kg='15'),
+        Bar(id=1, name="Men's Olympic", weight_kg='20', weight_lb='45'),
+        Bar(id=2, name="Women's Olympic", weight_kg='15', weight_lb='35'),
     ])
 
 

inventory/models.py

@@ -5,15 +5,12 @@ from common import remove_exponent, to_lb
 class Bar(models.Model):
     name = models.CharField(max_length=100)
     weight_kg = models.DecimalField(max_digits=7, decimal_places=3)
+    weight_lb = models.DecimalField(max_digits=7, decimal_places=3)
 
     def __str__(self):
         return '{} ({}kg / {}lb)'.format(self.name, remove_exponent(self.weight_kg),
                                          self.weight_lb)
 
-    @property
-    def weight_lb(self):
-        return to_lb(self.weight_kg)
-
 
 class Lift(models.Model):
     name = models.CharField(max_length=200)

lifting/models.py

@@ -1,3 +1,4 @@
+from decimal import Decimal
 from django.db import models
 from django.contrib.auth.models import User
 from django.contrib.postgres.fields import ArrayField
@@ -22,6 +23,18 @@ class LiftingOptions(models.Model):
     plate_pairs = ArrayField(models.DecimalField(max_digits=7, decimal_places=3),
                              default=['45','45','25','10','5','5','2.5','1.25'])
 
+    def plates_for_weight(self, weight):
+        side = []
+        w = initial_weight = Decimal(weight) - self.default_bar.weight_lb
+        available = sorted(self.plate_pairs, reverse=True)
+        while w and available:
+            plate = available.pop(0)
+            if plate * 2 <= w:
+                w -= plate * 2
+                side.append(plate)
+        if sum(side) * 2 != initial_weight:
+            raise ValueError('remaining weight {}'.format(initial_weight - sum(side) * 2))
+        return side
 
 class Set(models.Model):
     user = models.ForeignKey(User, related_name='sets')

lifting/tests.py

@@ -1,3 +1,4 @@
+from decimal import Decimal as D
 from django.test import TestCase
 from django.contrib.auth.models import User
 from lifting.models import LiftingOptions
@@ -5,6 +6,30 @@ from lifting.models import LiftingOptions
 
 class TestLiftingOptions(TestCase):
 
+    def setUp(self):
+        self.user = User.objects.create_user(username='test', email='test@example.com', password='test')
+
     def test_signal(self):
-        u = User.objects.create_user(username='test', email='test@example.com', password='test')
-        assert LiftingOptions.objects.filter(user=u).count() == 1
+        assert LiftingOptions.objects.filter(user=self.user).count() == 1
+
+    def test_plates_for_weight(self):
+        opts = self.user.lifting_options
+        opts.plate_pairs = [D(45), D(45), D(25), D(10), D(5), D(5), D('2.5')]
+        opts.default_bar_id = 1
+
+        assert opts.plates_for_weight(45) == []
+        assert opts.plates_for_weight(50) == [D('2.5')]
+        assert opts.plates_for_weight(90) == [D(10), D(5), D(5), D('2.5')]
+        assert opts.plates_for_weight(320) == [D(45), D(45), D(25), D(10), D(5), D(5), D('2.5')]
+
+    def test_plates_for_weight_error(self):
+        opts = self.user.lifting_options
+        opts.plate_pairs = [D(45), D(45), D(25), D(10), D(5), D(5), D('2.5')]
+        opts.default_bar_id = 1
+        # TODO: check amounts
+        with self.assertRaises(ValueError):
+            opts.plates_for_weight('47.5')
+        with self.assertRaises(ValueError):
+            opts.plates_for_weight(325)
+        with self.assertRaises(ValueError):
+            opts.plates_for_weight(30)